RPM's drop fast while shifting? Stock Flywheel - Scion tC Forums
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#1 (permalink) Old 03-24-2010, 12:55 AM
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I have a 2006 scion tc with a 5 speed at 50k miles. Lately I have been noticing that my RPM's are dropping really fast in between shifts and it has been messing up my timing when I release the clutch causing shock to the tranny. And I dont think this has been a problem before cause I usually let my car warm up but in the times that I do drive it when its not fully warmed up is when I notice the RPM's drop faster then they should when shifting. This concerns me just a tad bit, not sure if I should do a compression check or if its the flywheel/clutch.

I usually watch the RPM's when shifting and shift at 3k and let it drop to 2100 then engage smoothly. But, when the car isnt fully warm it goes down fast and this hasnt been a problem before. I dunno, maybe its just me. But, with stock flywheel my RPM's shouldnt be going down that fast.
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#2 (permalink) Old 03-24-2010, 02:21 AM
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That's normal, my car does that, only when it's cold. When it warms up, it'll slow down noticeably. I have an 08 with 9500 miles.

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#3 (permalink) Old 03-24-2010, 03:33 AM
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either you have a lightened flywheel
or you need to learn how to drive

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#4 (permalink) Old 03-24-2010, 06:09 PM
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Just compensate for the faster dropping revs, simple.

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#5 (permalink) Old 04-05-2010, 02:10 PM
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QUOTE (WavyTC08 @ Mar 24 2010, 02:09 PM)
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Just compensate for the faster dropping revs, simple. [/b]

Well I can drive stick, and I have a WRX with a lightweight flywheel and I can shift perfectly no problem in that car. But, now I realize that even when the car is warm the rpms drop really fast in between shifts. Should I do a compression check? Something wrong with the engine? Also should I look into idle air control valve to see if it needs to be replaced. There seems to be an underlying reason that this is happening.
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#6 (permalink) Old 03-21-2011, 12:58 AM
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This has been an on-going problem that comes stock in every tc i believe. Theres a delay somewhere being in the ECU or something that cause the RPMs to drop fast when you press the clutch in. I hate this personally because it feels like i just learned how to drive a manual when of course we literally have been driving stick all our lives.. Someone being on this forum or scionlife.com or clubsciontc.com has found a way to fix that but that requires some ECU work. Ill do some digging also because ive been getting tired of it also.
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#7 (permalink) Old 03-21-2011, 01:39 AM
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I always thought people complained about tC's RPM's not dropping fast enough..

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#8 (permalink) Old 03-22-2011, 10:25 AM
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Is it really a problem? I guess I'll check it out, but I'm "used" to the revs dropping like that, b/c it's my first car. Go figure.

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#9 (permalink) Old 03-22-2011, 06:07 PM
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There is no ongoing issue like was stated above. The car has a heavy flywheel. That makes rpm decrease more slowly than a lightweight unit would. The ecu is not the cause either. Rotational inertia and compression/backpressure are the big limiting factors in how fast engine speed drops when you let off. The flywheel has not gotten a bunch lighter by itself. So unless you have a huge drop in compression suddenly, which you would notice a lot in other ways, then the drop in engine speed has not changed.

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#10 (permalink) Old 03-22-2011, 06:16 PM
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Originally Posted by TrueHyperfox View Post
This has been an on-going problem that comes stock in every tc i believe. Theres a delay somewhere being in the ECU or something that cause the RPMs to drop fast when you press the clutch in. I hate this personally because it feels like i just learned how to drive a manual when of course we literally have been driving stick all our lives.. Someone being on this forum or scionlife.com or clubsciontc.com has found a way to fix that but that requires some ECU work. Ill do some digging also because ive been getting tired of it also.
The ecu can't make the revs drop faster. People claimed there was too much delay (it was slower not faster) due to the dbw when in fact the slower revving is due to the heavier flywheel. People and companies claim to have fixed this but it is simply not true. Want it to rev faster? Buy a lighter flywheel. People who would NOT want it to rev/decrease revs faster simply are not good at driving a stick (no matter how good they claim to be). I have never met a good driver that wanted rpms to increase or decrease more slowly ! In fact most spend good money to make that happen more quickly. That is the whole point of buying a light weight flywheel.

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Last edited by engifineer; 03-22-2011 at 06:19 PM.
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